System and method for efficient wakeup for beacon reception

ABSTRACT

According to an embodiment, a system and method is disclosed for efficient wake up in a wireless communication device for receiving beacons without significantly affecting the battery power and data throughput. Wireless device receives beacons from network elements such as access points. If beacons are not received as scheduled within defined intervals, then the wireless device determines a pattern of beacon reception timings and uses a weighted score process to select the best possible reception timing pattern and uses it as the schedule for receiving beacons on going forward basis, thus avoiding staying awake at all time to receive misaligned beacons.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/987,583, filed on Jan. 4, 2016, the entirety of which is incorporatedherein by reference.

TECHNICAL FIELD

This disclosure relates generally to the field of wireless communicationand more particularly to beacon reception in wireless communicationnetworks.

BACKGROUND

In wireless communication networks such as Wireless Local Area Networks(WLAN), communication management packets/frames are used to communicateinformation about the network. These frames are called beacons. Beaconsare transmitted by network elements such as Access Points (AP) andinclude basic information about the network such as network ID,communication parameters, supported data rates, network capability, andother relevant information needed for any wireless device for example,cell phones, PDAs, laptop computers, or any other device capable ofwireless communication in the network, to establish connection, stayconnected, and communicate with the network element.

Beacons are transmitted periodically at regular intervals (e.g., 100 ms,50 ms, 102.4 ms, 204.8 ms, or the like) in the network for wirelessdevices to maintain their connection with the network element andperform many other connection management related functions. Beaconinterval is communicated to wireless devices in the network at the timeof connection establishment so wireless devices can receive the beaconat a predetermined time and stay connected with the network element.Generally, the beacon interval is a default value selected by theequipment manufacturer of network elements and the interval remainsfixed in a network.

Typically, when a wireless device is in idle state and not performingany task, then to preserve battery power, the wireless devices goes to‘sleep’ in a power save mode and ‘wakes up’ after set a set interval,for example every 100 ms, to receive beacon from the network element andstay connected with the network. Although beacons are transmitted at aset interval, beacon intervals can drift due to various conditions suchas misalignment of clock synchronization, environmental conditions,network traffic congestion, and the like. In such cases, wirelessdevices can miss beacons and either assume that the network element isno longer available and start searching for another network element orstay awake and continue to monitor the network environment until theyreceive the next beacon. If beacon intervals drift for long period oftime, then to stay connected with the network, wireless devices stayawake and remain on a channel for the entire duration of beacon intervalto continuously monitor the network for beacons. When wireless devicesscan the network for beacons, they suspend sending and receiving datapackets because that requires wireless devices to change channel fordata transmission, which may result in wireless devices missing anotherbeacon. This causes wireless devices to lose battery power relativelyfaster when connected with the wireless network, especially with a WLANAP and it also affects the data throughput in the wireless network.

SUMMARY

In accordance with an embodiment an apparatus is disclosed. Theapparatus includes a transceiver, and a processing unit coupled to thetransceiver. The processing unit is configured to receive apredetermined number of beacons from a network element, determine areception timing pattern for the predetermined number of beacons, anduse the determined reception timing pattern for receiving furtherbeacons from the network element, wherein at least one beacon of thepredetermined number of beacons is received prior to or after ascheduled reception time for the at least one beacon.

In accordance with another embodiment, a method is disclosed. The methodincludes receiving by a processing unit, a predetermine number ofbeacons from a network element, determining a reception timing patternfor the predetermined number of beacons, and using the determinedreception timing pattern for receiving further beacons from the networkelement, wherein at least one beacon of the predetermined number ofbeacons is received prior to or after a scheduled reception time for theat least one beacon.

In accordance with yet another embodiment an apparatus is disclosed. Theapparatus includes a transceiver for transmitting and receiving datapackets, and a processing unit coupled to the transceiver and configuredto, receive a predetermined number of beacons from a network element,determine reception timing patterns for the predetermined number ofbeacons, determine a score for each one of the reception timingpatterns, and use a reception timing pattern with at least one of alowest score or a highest score for receiving further beacons from thenetwork element, wherein at least one beacon of the predetermined numberof beacons is received prior to or after a scheduled reception time forthe at least one beacon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary wireless network according to anembodiment.

FIG. 2A-C illustrate exemplary patterns of beacon reception timingsaccording to another embodiment.

FIG. 3 illustrates an exemplary flow diagram for determining amisaligned beacon pattern for efficient wakeup according to anembodiment.

DETAILED DESCRIPTION

The following description provides many different embodiments, orexamples, for implementing different features of the subject matter.These descriptions are merely for illustrative purposes and do not limitthe scope of the invention.

Referring to FIG. 1, an exemplary wireless network 100 is illustratedaccording to an embodiment. Network 100 includes a network element 110.The network element 110 can be any wireless communication networkelement for example, an access point, a network relay, a networkextender, a wireless router, or any other device capable of connectingto a network and provide wireless communication connections to variousdevices. The network element 110 includes a transceiver 112, a processor114, a storage device 116, and an antenna 118 among various other systemcomponents. Although for explanation, simple elements are shown;however, the network element 110 can have various others systemcomponents and multiple elements for example, the network element 110can have multiple processors, antennas, storage devices, transceivers,displays, user interface, and the like.

The network element 110 is communicatively coupled to a backend networkdevice 120 and a network 130. The network element 110 can be coupled tovarious other networks and systems to provide network services forexample, network element 110 can be connected to content servers,Internet, cellular networks, media service providers, routers, and thelike. Further, the network element 110 can be connected to these systemsvia wireline or wireless communication links or combination thereof. Thenetwork 100 includes various wireless communication devices such as forexample, a cell phone 140, a laptop computer 150, and a personal digitalassistant device (PDA) 160. The network 100 can also include many otherdevices capable of wirelessly communicating with the network element 110such as control systems, printers, consumer electronic devices, andvarious other devices and systems. Further, the network element 110 canalso be communicatively coupled to other network elements in a meshnetwork scheme. Each of these devices, such as the cellular phone 140may also include various other system components such as a transceiver142, a processor 144, storage devices 146, and other components likedisplays, keyboards, an antenna, and the like (not shown).

When a wireless device, such as for example the cell phone 140,establishes a communication with the network element 110, then thenetwork element 110 provides various communication related parameters tothe cell phone 140 for the cell phone 140 to effectively communicatewith the network element 110. Among many other parameters, the networkelement 110 also provides beacon interval information to the cell phone140.

For example, if the manufacturer of the network element 110 sets thebeacon interval for network element 110 at 100 milliseconds (100 ms),then the network element 110 provides that information to the cell phone140. The beacon information can be provided to the cell phone 140 invarious ways according to the wireless communication protocol that isused to establish the communication for example, if the network element110 and the cell phone 140 are capable of communicating with each otherusing IEEE 802.11 WLAN protocol, then the beacon information will beprovided in a Target Beacon Transmission Time (TBTT) field of themanagement frame. Similarly, for other wireless communication protocolsthat use beacons for connection management, this information can beprovided to the cell phone 140 in appropriate fields of the protocolspecific management frames.

In the present example, after receiving the beacon information, the cellphone 140 monitors the channel every 100 ms to receive a beacon from thenetwork element 110. After receiving the beacon, if the cell phone 140is not actively processing any data, then the cell phone 140 goes into apower saving idle mode to preserve battery power and wakes up again ateach 100 ms interval to receive the beacon from network element 110.Typically, electronic signals include jitters, which may cause signalmisalignment. Electronic devices typically include a mechanism to adjustminor jitters in the electronic signals; however, if the signal ismisaligned for more than any given threshold, which cannot be adjusted,then the signal connection is reestablished to resynchronize the signalreception.

As explained hereinabove, in conventional wireless networks, when abeacon is not received as scheduled, then the cellular phone 140 doesnot drop the connection with the network element 110 but instead staysawake to monitor the channel for the next beacon from the networkelement 110. If beacons from the network element 100 are misaligned withthe scheduled timing for receiving beacons (e.g., 100 ms), then thecellular phone 140 may end up staying awake longer to ensure it receivesbeacons from the network element 110 and maintains a proper connectionwith the network element 110. This causes the cellular phone 140 to losesignificant amount of battery power just for receiving beacons andresults in poor data throughput. According to an embodiment, when thecellular phone 140 does not receive a beacon as scheduled, the cellularphone 140 initiates an efficient wakeup process to capture beacons fromthe network element 110 without staying awake for long time andpreserves battery power.

Referring to FIG. 2A, an exemplary beacon reception timing pattern 200Ais illustrated according to another embodiment. The illustrated beaconreception timing pattern 200A can be observed at any wireless device forexample cellular phone 140 (or computer 150, PDA 160, or the likedevices) while communicating with a network element such as the networkelement 110. The beacon reception timing pattern 200A includes timeswhen beacons are received at the wireless device. Beacons A-E areexpected to be received at the wireless device at timings 210 a-210 erespectively with respective beacon intervals 214-217 according to thewireless connection parameters. Timings 212 a-212 e are the actualtimings when beacons A-E are received by the wireless device. Asillustrated, beacons A-E are received with a little jitter; however, thewireless device is able to adjust the jitter and receives the beaconwithout any significant timing issue. In this example, the wirelessdevice continues to wake up after given intervals 214-217 and receivesbeacons A-E as expected.

Typically, beacons are misaligned because of various reasons such asclock misalignment, change in the physical environment of the network,or the like. For example, if some physical structure temporarilyobstructs the line of sight for the network element and its transmissionhas to bounce off of the physical structure before it reaches thewireless device with some delay, then that transmission pattern mostprobably remains the same for a period of time until the obstruction isremoved. Similarly, if there are other causes of misalignment of beaconreception, then the misaligned beacon reception pattern remains the sameuntil the causes of misalignment are removed.

Referring to FIG. 2B, an exemplary beacon reception timing pattern 200Bwith misaligned beacon reception is illustrated according to anotherembodiment. As illustrated, beacons A-E are scheduled to be received attimes 220 a-220 e; however, beacon A is received at time 222 a, which is4 ms prior to the scheduled reception time 220 a, beacon B is receivedas scheduled, beacon C is received at time 222 c, which is 4 ms prior tothe scheduled time 220 c, beacon D is received as scheduled, and beaconE is received at time 222 e, which is 4 ms prior to the scheduled time220 e. Conventionally, a wireless device wakes up at time 220 aexpecting the beacon A; however, because the beacon A arrived at time222 a, which is 4 ms prior to the scheduled time 220 a, the wirelessdevice misses the beacon A and stays awake in full power mode until itreceives beacon B, which is received as scheduled at time 220 b. Afterreceiving the beacon B, the wireless device goes back to ‘sleep’ and‘wakes up’ at time 220 c to receive beacon C; however, the beacon Carrived at time 222 c, which was 4 ms prior to the scheduled time, thewireless device misses the beacon C and stays ‘awake’ to receive beaconD. In this example, because the wireless device is not receiving beaconsas scheduled, the conventional wireless device stays awake after missinga beacon to continue to capture misaligned beacons and uses up systemresources and battery power.

Referring to FIG. 2C, an exemplary beacon reception timing pattern 200Cwith different misaligned beacon reception pattern is illustratedaccording to yet another embodiment. As illustrated, beacons A-E arescheduled to be received at times 230 a-230 e; however, beacon A isreceived at time 232 a, which is 4 ms prior to the scheduled receptiontime of 230 a, beacon B is received 8 ms prior to scheduled time at time232 b, beacon C is received as scheduled, beacon D is received 4 msprior to scheduled time at time 232 d, and bacon E is received at time232 e, which is 8 ms prior to the scheduled time 230 e. As explained inthe previous example, a conventional wireless device will stay ‘awake’after missing a beacon to continue to receive misaligned beacons and useup significant battery power.

A wireless device according to an embodiment, stays awake after missinga beacon to receive a predetermined number (e.g., 10, 20, 30, 50, or thelike) of misaligned beacons and then determines a misalignment patternfor beacon reception. Based on the determination and contrary to therecommended wakeup time communicated by the network element during theconnection establishment process, the wireless device adjusts its wakeuptime to align its wakeup time with the misaligned pattern of beaconreception timing. This allows the wireless device to save significantamount of battery power by avoiding staying awake to receive misalignedbeacons for the wireless connection as typically done in conventionalwireless devices.

According to an embodiment, when the wireless device determines thatbeacons have multiple reception patterns, then the wireless devicemonitors misaligned beacon reception timing patterns and calculates abest weighted pattern for the next beacon and follows the weighted timepattern until the beacon reception pattern changes again. For example,in exemplary illustrations of FIGS. 2A-C, beacons are received accordingto some repetitive patterns. Each pattern can be considered as ahypothesis and any statistical weighting mechanism can be used todetermine the most likely occurrence of a given pattern and then thatgiven pattern can be used as wakeup time pattern for the wireless deviceto receive beacons.

In an embodiment, beacon arrival times can be analyzed with respect toeach of the patterns from FIGS. 2A-C in parallel. Each pattern then canbe scored according to the actual arrival time versus expected arrivaltime. One of the many possible score calculation methods can be asfollows:

Score=Score+α(|T1−T2|−Score)

T1=Actual beacon arrival timeT2=Expected beacon arrival timeα=score factor

In exemplary embodiment, score value can be initialized to zero andincreased as beacon patterns are captured. After a predetermined numberof beacons, if the score is below some threshold such as for examplebelow 5000, this may indicate that a beacon pattern has been detected.After the initial detection, the detected pattern can be used for futurebeacon detection. The beacon pattern is periodically monitored andtracked to ensure that the pattern does not change for example, duringperiodic monitoring and tracking, if it is determined that the scoreremains below for example, the previously used threshold 5000, then thepossibility is that the beacon pattern has not changed and the currentpattern will be used to continue to detect beacons. If for some reasonthe score exceeds the previously captured threshold (e.g., 5000), thenit may indicate that the beacon pattern track has been lost and the newacquisition phase can be restarted. Also, when a pattern is used toreceive beacons and a beacon is missed, then it may indicate that thetracking of the pattern is lost or the pattern has changed for variousreasons and the process for new pattern acquisition can be restarted.

The term ‘score factor’ in the above equation determines algorithm'ssensitivity to irregular delays that can be added on top of the detectedpattern due to certain network events. In some exemplary implementation,a score factor of ⅛ can be used. Other score factors such as ¼, 1/7,1/10, 1/16, 1/20 or the like can also be used. As the score factor getshigher the score will tend to bounce and beacon patterns may becomechallenging to monitor and track.

As the score gets lower, the calculation more closely tracks the arrivalpattern of beacons. If the score gets higher, then it can reflect arandom beacon intervals pattern, which eventually leads to thetraditional wake up method. One skilled in the art will appreciate thatan exemplary weighted score method is illustrated for determiningweighted beacon pattern; however, the method is not limited to anyparticular weighted score scheme. Any statistical method can be used todetermine the success of the best hypothesis to be used as beaconreceiving schedule.

Referring to FIG. 3, a flow diagram for a process 300 for determining abeacon reception timing is illustrated according to another embodiment.When a wireless device receives a beacon at 310 from a network elementfor example, an access point, then at 320, the wireless devicedetermines whether the beacon is misaligned from scheduled timing. Ifthe beacon is not misaligned and is received as scheduled, the wirelessdevice continues to receive beacons as scheduled. If the beacon is notreceived as scheduled and it is misaligned from the actual scheduledtime, then at 330, the wireless device receives a predetermined number(e.g., 10, 20, 30, 50 or the like) of beacons.

The wireless device at 340 determines whether there is a pattern ofmisalignment for beacon reception timings. If there is no pattern andbeacons are randomly misaligned, then at 350, the wireless devicereverts to conventional scheme of staying awake to receive misalignedbeacons. If the wireless device determines that there is a pattern inreceiving misaligned beacons, then at 360, the wireless devicedetermines the pattern such as for example illustrated in FIG. 2B orFIG. 2C. The wireless device further determines at 370 if there are morethan one pattern of misalignment of beacon reception timings. If thereare no more than one pattern, then at 395, the wireless device uses thedetermined pattern of receiving beacons as schedule for receiving futurebeacons. If there are more than one misalignment patterns, then at 380,the wireless device calculates a weighted score for each pattern. Asexplained above, the weighted score can be determined using variousstatistical methods. After determining the weighted score, at 390, thewireless device selects the best pattern to use for beacon receiving andat 395, the wireless device uses misaligned pattern with the best scoreas the schedule for receiving beacons from the network element.

The foregoing outlines features of several embodiments so that those ofordinary skill in the art may better understand various aspects of thepresent disclosure. Those of ordinary skill in the art should appreciatethat they may readily use the present disclosure as a basis fordesigning or modifying other processes and structures for carrying outthe same purposes and/or achieving the same advantages of variousembodiments introduced herein. Those of ordinary skill in the art shouldalso realize that such equivalent constructions do not depart from thespirit and scope of the present disclosure, and that they may makevarious changes, substitutions, and alterations herein without departingfrom the spirit and scope of the present disclosure.

Although the subject matter has been described in language specific tostructural features or methodological acts, it is to be understood thatthe subject matter of the appended claims is not necessarily limited tothe specific features or acts described above. Rather, the specificfeatures and acts described above are disclosed as example forms ofimplementing at least some of the claims. Various operations ofembodiments are provided herein. The order in which some or all of theoperations are described should not be construed to imply that theseoperations are necessarily order dependent. Alternative ordering will beappreciated having the benefit of this description. Further, it will beunderstood that not all operations are necessarily present in eachembodiment provided herein. Also, it will be understood that not alloperations are necessary in some embodiments.

Moreover, “exemplary” is used herein to mean serving as an example,instance, illustration, etc., and not necessarily as advantageous. Also,although the disclosure has been shown and described with respect to oneor more implementations, equivalent alterations and modifications willoccur to others of ordinary skill in the art based upon a reading andunderstanding of this specification and the annexed drawings. Thedisclosure comprises all such modifications and alterations and islimited only by the scope of the following claims. In particular regardto the various functions performed by the above described components(e.g., elements, resources, etc.), the terms used to describe suchcomponents are intended to correspond, unless otherwise indicated, toany component which performs the specified function of the describedcomponent (e.g., that is functionally equivalent), even though notstructurally equivalent to the disclosed structure. In addition, while aparticular feature of the disclosure may have been disclosed withrespect to only one of several implementations, such feature may becombined with one or more other features of the other implementations asmay be desired and advantageous for any given or particular application.

What is claimed is:
 1. An apparatus comprising: a transceiver; and aprocessing unit coupled to the transceiver and configured to, receivefrom a network element a beacon; determine whether the beacon ismisaligned from scheduled timing; when the beacon is not received asscheduled and is misaligned from scheduled timing, receive apredetermined number of additional beacons: determine whether at leastone the additional beacons are misaligned; when an additional beacon ismisaligned: calculate a weighted score for the misaligned, additionalbeacon; select a misalignment pattern based on the weighted scores; andreceiving another beacon using the selected misalignment pattern.
 2. Theapparatus of claim 1, wherein the weighted score is based at least on aprobability of repeating a beacon misalignment.
 3. The apparatus ofclaim 1, wherein each beacon in the one or more predetermined number ofadditional beacons arrive in intervals of at least one of the following:50 milliseconds; 100 milliseconds; 102.4 ms; and 204.8 ms.
 4. A methodcomprising: receive from a network element a beacon; determine whetherthe beacon is misaligned; when the beacon is not received as scheduledand is misaligned from scheduled timing, receive a predetermined numberof additional beacons; determine whether at least one the additionalbeacons are misaligned; when an additional beacon is misaligned:calculate a weighted score for the misaligned, additional beacon; selecta misalignment pattern based on the weighted scores; and receivinganother beacon using the selected misalignment pattern.
 5. The method ofclaim 4, wherein the weighted score is based at least on a probabilityof repeating a beacon misalignment.
 6. The method of claim 4, whereineach beacon in the one or more predetermined number of additionalbeacons arrive in intervals of at least one of the following: 50milliseconds; 100 milliseconds; 102.4 ms; and 204.8 ms.